The U.S. government is reconstituting its fallout analysis capabilities as one long-term response to terrorists considering detonating a nuclear weapon or radiological "dirty bomb" on American soil. Rebuilding started five years ago with the hiring of new experts and calling in old-timers to share and update a knowledge base that had been left to decay after the end of the Cold War and underground testing by other nations. The last above-ground nuclear test was conducted in 1980.
Fallout analysis or "Post-event forensics" examines the dust and isotopes created after a nuclear blast and can be used to fingerprint a weapon's type and characteristics, allowing fissionable materials to be identified to country of origin. Debris signatures can be matched with libraries of classified data about nuclear arms around the world to identify known devices, but improvised devices are unlikely to fit documented profiles incorporating data on fallout signature, characteristics, and construction materials. Scientific advisory groups view developing and more importantly declaring the existence of fallout analysis could deter attackers and bolster threats of retaliation.
It would likely promote more responsibility with potential fissionable material producers to keep track of and hold onto their stores, rather than to sell them to a third party. If an improvised device were to use materials that could be traced back to their source, the penalties would likely be most severe.
New faces from the Department of Homeland Security and the FBI have been incorporated into the Defense Threat Reduction Agency's efforts to increase the flow of intelligence on foreign nuclear arms and potential threats to the United States. Should the unthinkable occur, a rush for retribution against a nuclear attack would press officials to quickly try to identify the attackers. Federal experts are also concerned about complex threat scenarios, such as an American warhead being stolen and detonated in an American city.
New robots and a new aircraft for atmosphere sampling of nuclear fallout are currently in the works. A robot would go into a hot area to collect samples and return them for analysis and also provide some on-the-spot results via radio. The Air Force currently operates a single modified C-135 called Constant Phoenix for atmospheric sampling and is likely examining UAV options for the mission. Doug Mohney